1. Field of the Invention
The present invention relates to a substrate processing apparatus.
2. Description of the Related Art
In a photo resist process of a semiconductor device fabrication, resist solution is coated on a substrate (for example, a semiconductor wafer--hereinafter referred to as wafer) and a resist film is formed thereon. The resist film is exposed with a particular pattern. The resultant wafer is developed with a developing solution. In a sequence of such steps, a coating/developing apparatus has been used.
The coating/developing apparatus has various liquid process units and various heat treatment units. The liquid process units are for example a resist coating unit (that coats a resist solution to a wafer and forms a resist film on the wafer) and a developing unit that develops a wafer that has been exposed. The heat treatment units are for example a heating unit (that heats a wafer coated with a resist film) and a cooling unit (that cools a wafer that has heated). The liquid process units and the heat treatment units are piled up so that the installation space in the coating/developing apparatus is reduced. A wafer is conveyed to each liquid process unit and each heat treatment unit by conveying units. In other words, the coating/developing apparatus, the liquid process units, heat treatment units, and conveying units are integrally disposed in the coating/developing apparatus.
However, as the diameters of wafers becomes large, the sizes of heat treatment units and liquid process units are increased. Thus, since heat treatment units and liquid process units are more integrally disposed in a coating/developing apparatus, heat generated by heating units tends to adversely affect liquid process units. In addition, as the sizes of heating units as heat sources increase, the amount of heat generated by the heating units also increases. Consequently, the liquid process units are adversely affected by heat. For example, the film thickness of a resist film formed by a resist coating unit will vary.